I. Field of the Invention
The invention relates to a staple cartridge and feed means and more particularly to a staple cartridge well suited for use with a surgical stapling instrument.
II. Description of the Prior Art
While the staple cartridge and feed means of the present invention is capable of many applications, it will, for purposes of an exemplary showing, be described in terms of its use with a surgical stapling instrument for which it is particularly well adapted. Recently, surgeons have come more and more to the use of staples, rather than conventional thread sutures, for closing wounds or incisions in the skin and fascia of a patient. This trend is due largely to the fact that the use of staples is a far easier procedure and, of even greater importance, is very much faster. This substantially reduces the time required for suturing and the length of time the patient must be maintained under anaesthesia.
Prior art workers have developed various types of surgical stapling instruments and staple cartridges for use therewith. Of particular concern has been the staple feed means within a cartridge and numerous approaches have been taken by prior art workers. For example, cartridges have been devised wherein the staple feed means comprises a pair of staple-advancing screws. The staples are retained by and advanced by the threads of the pair of staple-advancing screws and it will be appreciated that the pair of screws must be turned very precisely to prevent jamming of the staples within the cartridge. As a consequence, complex gear means or cam means are required to turn the staple-advancing screws. Examples of such cartridges are taught in U.S. Pat. Nos. 3,618,842 and 3,643,851.
Another approach is taught in U.S. Pat. No. 3,638,847 wherein the cartridge is provided with a stationary sawtooth staple-retaining member and a reciprocating sawtooth staple advancing member adapted to cooperate with the staple former or pusher. U.S. Pat. No. 3,650,453; 3,717,294 and 3,837,555 teach yet another approach wherein a plurality of staples are guided and advanced by a continuous belt adapted for rotation within the cartridge. The belt and staples mounted thereon are advanced by the action of the staple former or by the inter-action of the staple former and the forwardmost staple.
It will be evident from the foregoing that prior art staple cartridge and feed means have been complex in construction and difficult and expensive to manufacture. The complexity of the feed means has had a direct bearing on the reliability of prior art cartridges, it being understood by one skilled in the art that once a staple has jammed within the cartridge, the cartridge and its remaining staples cannot be further used. The complexity of prior art staple cartridge and feed means has been reflected in the complexity and expense of the surgical stapling instruments with which the cartridges are used. The use of complicated gear means or the staple former itself to advance the staples within the cartridge has required considerable power from the surgical stapling instrument.
The present invention is based upon the discovery that a very much simpler, less expensive, and more reliable staple cartridge can be achieved by providing a vertical staple feeding track to accommodate a plurality of staples and spring means to advance the staples therein; a separate vertical, parallel staple forming track housing a reciprocating staple former; a window providing a horizontal passage between the two tracks and sized to permit a single staple to pass therethrough; means to normally maintain the staples within the staple feeding track; positive means to selectively shift a single staple from the staple feeding track through the window to the staple forming track and means to maintain such a shifted staple in proper position within the staple forming track for engagement by the staple former. The provision of vertical staple feed means and horizontal staple feed means which are independent of each other and independent of the staple former results in an arrangement in which the staples are far less likely to become jammed. In this arrangement the staple feeding portion of the cartridge cycle is completed before the start of the staple forming portion of the cartridge cycle.
The cartridge of the present invention requires less power from the surgical staple instrument to operate it. The staple feeding means is extremely reliable with the result that staples can be consistently and accurately formed about the anvil of the surgical stapling instrument.